From 7b38def8e0b00abb5bdd36dcc8d030612d1d7138 Mon Sep 17 00:00:00 2001
From: Havard Graff <havard.graff@gmail.com>
Date: Sun, 3 Nov 2019 12:55:13 +0100
Subject: [PATCH] structure: add gst_structure_take
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(╯°□°）╯︵ ┻━┻
---
 gst/gststructure.c | 41 +++++++++++++++++++++++++++++++++++++++++
 gst/gststructure.h |  3 +++
 2 files changed, 44 insertions(+)

diff --git a/gst/gststructure.c b/gst/gststructure.c
index fafaa65c33..4288c4a4ee 100644
--- a/gst/gststructure.c
+++ b/gst/gststructure.c
@@ -418,6 +418,47 @@ gst_clear_structure (GstStructure ** structure_ptr)
   g_clear_pointer (structure_ptr, gst_structure_free);
 }
 
+/**
+ * gst_structure_take:
+ * @oldstr_ptr: (inout) (transfer full) (nullable): pointer to a place of
+ *     a #GstStructure to take
+ * @newstr: (transfer full) (allow-none): a new #GstStructure
+ *
+ * Atomically modifies a pointer to point to a new object.
+ * The #GstStructure @oldstr_ptr is pointing to is freed and
+ * @newstr is taken ownership over.
+ *
+ * Either @newstr and the value pointed to by @oldstr_ptr may be %NULL.
+ *
+ * Returns: %TRUE if @newstr was different from @oldstr_ptr
+ *
+ * Since: 1.18
+ */
+gboolean
+gst_structure_take (GstStructure ** oldstr_ptr, GstStructure * newstr)
+{
+  GstStructure *oldstr;
+
+  g_return_val_if_fail (oldstr_ptr != NULL, FALSE);
+
+  oldstr = g_atomic_pointer_get ((gpointer *) oldstr_ptr);
+
+  if (G_UNLIKELY (oldstr == newstr))
+    return FALSE;
+
+  while (G_UNLIKELY (!g_atomic_pointer_compare_and_exchange ((gpointer *)
+              oldstr_ptr, oldstr, newstr))) {
+    oldstr = g_atomic_pointer_get ((gpointer *) oldstr_ptr);
+    if (G_UNLIKELY (oldstr == newstr))
+      break;
+  }
+
+  if (oldstr)
+    gst_structure_free (oldstr);
+
+  return oldstr != newstr;
+}
+
 /**
  * gst_structure_get_name:
  * @structure: a #GstStructure
diff --git a/gst/gststructure.h b/gst/gststructure.h
index 8df9bc3bb9..a267bc8735 100644
--- a/gst/gststructure.h
+++ b/gst/gststructure.h
@@ -137,6 +137,9 @@ GST_API
 void                  gst_clear_structure                (GstStructure **structure_ptr);
 #define               gst_clear_structure(structure_ptr) g_clear_pointer ((structure_ptr), gst_structure_free)
 
+GST_API
+gboolean              gst_structure_take                 (GstStructure ** oldstr_ptr,
+                                                          GstStructure * newstr);
 GST_API
 const gchar *         gst_structure_get_name             (const GstStructure  * structure);